Control and equalizing system



June 29 1926. 1,590,507

E. HELLMUND CONTROL AND EQUALIZING SYSTEM Filed A i-i1 14, 1920 WIINESSES: INVENTOR 3 /ATTORNEY Patented June 29, 1926.

UNITED STATES RUDOLF E. HELLMUND, OF SWISSVALE, PENNSYLVANIA.

CONTROL AND EQUALIZING SYSTEM.

Application filed April 14, 1920. Serial' No. 373,959.

My invention relates to electric railway systems, and it has for its object to provide means whereby electric locomotives may be conveniently started and whereby the speed, power-factor and load distribution in a plurality of motors may subsequentlv be regulated.

In the accompanying drawings. Fig. 1 is a diagrammatic view or" the electrical equipment of a railway locomotive supplied with polyphase induction motors, constructed in accordance with one embodiment of my in vention: Fig. 2 is a diagrammatic view of a system similar to that shown in Fig. 1, embodying a modification of my invention: and Fig. 3 is a side view, in elevation, of a locomotive wherein my invention would find application.

In the operation of electric railway systems it is desirable to employ alternating current on the trolley because of the economy and simplicity of an alternating-current distributing system, and the poly phase induction motor is commonly employed with electric railway systems of this character, especially for heavy freight service where recuperation is desirable. In those systems wherein a single-phase trolley is employed, it is necessary to provide a phase splitter, preferably of the rotary type, for the derivation of suitable current for the motors.

The polyphase induction motor is essentially a single-speed machine and, in order to provide flexible speed regulation therefor, it has been common practice to provide cascading arrangements in connection with adjustable secondary-resistance members with attendant heavy losses. It is, therefore, desirable to equip a railway vehicle with energy-changing apparatus, whereby energy derived from the secondary members of the induction motors, in the speed regulation thereof. may be usefully employed. Furthermore, it is extremely difiicult to maintain the driving wheels of a heavy electric vehicle, such, for example, as a locomotive, at the same diameters because of uneven wear and because of the heavy machining necessary, in some cases, to removedefects, such as flaws and flat spots, Asaresult, the induction motors connected to two driving wheels of different diameters would tfend to operate at different speeds, and the slight resulting differences in slip frequencies would cause a radical difference in' the torques e rte we so e; -wie' eseee' eequal distribution of the load and serious heating in the overloaded motors. It is desirable, therefore, to equip the vehicle with apparatus for power-equalizing purposes and, in addition, apparatus would be iiistalled for improving the power factor in the motors for economy in power transmission. By my invention, I provide two sets of auxiliary apparatus on a railway vehicle which will accomplish all of the above-men tioned results in an. effective manner, with considerable saving in weight and complexity of circuits.

Referring to 1 of the accompanying drawings for a more detailed understanding of my invention, an induction motor of the polyphase, wound-secondary type is shown at 4 and comprises a primary member 5 and a secondary member 6. A similar companion induction motor 7 is provided with a primary member 8 and with a secondary member 9. The secondary member 6, which, in this case, isshown as the rotor, is connected to a drive wheel 10, and the secondary member 8 is connected to a drive wheel 11. As shown, the drive wheel 10 is larger than the drive wheel 11, although the difference in size shown is greatly exaggerated with respect to that which would be encountered in actual prac tice.

The primary windings 5 and 8 are connected to derive energy from polyphase mains 12 which may be connected either to a polyphase distributing system or which may be energized from a single-phase distributing system through a suitable phasesplitter.

The terminals of the secondary winding 6 are connected, respectively, to the brushes of a dynamo-electric machine 13 of the poly phase commutator type. In like manner, the terminals of the secondary windings 9 are connected, respectively, to the brushes of a polyphase commutator machine 15 which is also provided with slip rings 16. The machines 13 and 15 are mechanically coupled for the interchange of energy therebetween, and the slip rings 16 are connected to adjustable pointsin the transformer 17 which is also connected to the mains 12, whereby the voltage of thealternating currents supplied to'th'e armature of machine v15 through said slip rings may be adjusted.

' Having thus described the structure and arrangement ofa system embodying my .in-

vention, the operation thereof is as follows: The tendency of the rotor of motor connected to a small drive wheel is to operate at high speed with small slip and, in a like manner, the tenden y of rotor connected to a large drive wheel is to operate at low speed with heavy. slip. The shape of the speal-toro 'ue curves oi induction motors such that the decrease in energy output of one of said machines, because o't its slightly lower speed, is far more than compensated for by the largely increased torque due to the greater slip. As a result, the secondary member 6 connected to the large dr ve wheel tends to have a much heavier output than does the secondary member 8. By the s, tem shown, however, the torque ot tie menrher 6 is red ced by supplying energy to the polyphase nachine 13 which operates as a motor, oriving the machine a generator and causing it to supply energy to the secondary member 9, an in crease the torque thereof, anc, by adjustment, an increase of energy to motor 7, and the decrease of output demanded from the ureter l causes equalization in the power output or said two machines.

As will he noted, the two commutator machines are excited in accordance with the vol 'es oil the secondary windings of the respective motors. This arrangement is set ist'aotory except in the particular case in which the speed cit motor 7 is such that the 'oltage induced in the rotor 9 is practically all absorbed by the ohmic drop and lcasage inductance of: this ci"cuit. .ln this cas the voltage across the st tor winding oi the mach ne 15 woul be practically Zero, leaving the machine without excitation. Similar conditions may or when the motor happens to run at synchronous speed, in which tesc no voltage is induced in its secondary member By inii iressing, in this case, a voltage from the transformer 17 upon the slip rings 16, it is possible, nevertheless, to have an external volt pressed upon the rotor a. thereliiy in ecting into the circuit for the purpose oi the speed ot motor T towards or nchronous speed, the case may be. Jerly controlling; such energy, the c motor 7 may be raised, througl'i ciencychanger the mauntil the ener onal r of the machine 13. Alt action has been accomplisl ed, the transformer 17 does not necessarily have to be in operative connection, although its presence is not objectionable ever. under this condition.

it to be understood, of course, that,

lon as the transformer 17 is o erativelv connected to the slip-rings 13 the speed of e same as that of the motor 7. Such ad ustment can always be brought about by regulating both or either of the stator windings of the machines 13 and 15 ii of power-factor compensation in the main motors l adjusting the position of the brushes of the commutator machines and by adjustments the impedance devices 21 in the stator circuits.

In so far as the secondary voltage of the transformer 17 indirectly governs the volte of the machine 15 to a large extent, it governing influence upon will also have the speed of the motor ble to adjust the speed of the motor 7 by adjusting the voltage of the transformer taps. Such adjustment may cause a flow of energy from the transformer into the motor 7 through the machine 15 and thus change the load of themachine 18; but it is always possible to subsequently readjust the machine13 so that the energy derived from the notor s is nearly all absorbed, by reason of the energy that is supplied to the motor 7, which is the most desirable condition of operation.

It may, however, at times, be desirable to operate at speeds different from those speeds at which such ideal operation is possible, and, in such cases, the difference of energy can always be conveniently derived from the transformer 17 or delivered to this transformer. It desirable, it is even possible to use the auxiliary machines 13 and 15 for the entire soced regulation of the main motors. In this case, both motors will o f course, deliver energy to the commutator machines during acceleration. Such electrical energy, derived from the motor 4:, is transformed into mechanical energy in the machine 13 and transferred as such into machine 15, being electrically transmitted therefrom through the slip-rings 16 to the transformer 17. On the other hand, the energy derived from the machine 7 by the machine 15 is transmitted directly to the slip-rings 16 and from there into the transformer 17. The existence of the transformer 17 is, therefore, advantageous from several points of view.

Referring to the form of my invention shown in Fi 2, the secondary member 6 is connected to the alternating-current end of a rotary converter 18, and the secondary member 9 is connected to the alternatingcurrent end of a rotary converter 19. The

two rotary converters l8 and 19 are electrically connected at their direct current ends so that there is an electrical interchange similar to the mechanical interchange between the machines 13 and. 15 f .F '1.

. It is thus POSSIL An adjustably connected storage battery 20 is preferably floated across the direct-current interchange mains in order to maintain more stable conditions.

A system of the character described is also capable of application in the equalization of the power output of motors carried by two different propulsive units which may be jointly operated and, in this case, the system of Fig. 2, wherein there is an electrical transfer of energy, is obviously much more readily applicable.

lVhile I have shown my invention in two of its preferred forms, it will be obvious to those skilled in the art that it is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that; only such limitations shall be placed thereupon as are imposed by the prior art or art specifically set forth in the appended claims.

I claim as my invention:

1. The combination with a plurality of similar induction motors, of a common load supplied thereby, means for causing said motors to operate at different speeds, whereby said load tends to become unequally divided, and means for equalizing said load distribution comprising auxiliary dynamo electric machines.

2. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of different diameters connected thereto, of means for deriving energy from a motor which operates more slowly and supplying said energy to a motor which tends to operate more rapidly.

3. The combination with railway propulsion apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of. different diameters connected thereto, of means for simultaneously decreasing the torque of one motor and increasing the torque of another motor thereby to equalize the loads.

4. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors ofthe induction. type and drive wheels of different diameters connected thereto, of means for simultaneously increasing the torque of a motor connected to a small drive wheel and for de creasing the torque in a motor connected to a large drive wheel and for transferring energy from said latter motor to said first named motor.

5. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of different diameters connected thereto, of means for deriv ing energy from the secondary member of a motor connected to a large drive wheel and for en l in said ener Y to the secondar P 5 i: b v

member of a motor connected to a small drive wheel.

6. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of different diameters connected thereto, of two auxiliary dynamically associated dyni'inio-electric machines. and means for supplying energy derived from the secondary member of a motor connected to a large drive wheel to one of said auxiliary dynamoelectric machines, driving the second aui-ziliary dynamo-electric machine thereby and supplying electrical energy generated in said second dynamo-electric machine to the secondary nien'ilter of a motor connected to a small drive wheel.

7. The combination with raili'vay. propulsive apparatus embodying a plurality of similar propulsion motors of the induct on type and drive wheels of different d instem connected thereto, of twodynamically associated polyphase commutator machines, and means for supplying energy derived from the secondary member of a motor connected to a large drive wheel to one of said auxili ary polyphase commutator machines, driving the second polyphase commutator machine thereby, and supplying energy generated in said second machine to the secondary member of a motor connected to a small drive wheel.

8. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of different diameters connected thereto, of two dynamically associated polyphase commutator machines, and means for supplying energy derived from the secondary member of a motor connected to a large drive wheel to one of said auxiliary polyphase commutator machines, driving the second polyphase comn'iutator machine thereby, and supplying energy generated in said second machine to the second ary member of a motor connected to a small drive wheel, and means for varying the ex citation of said polyphase connnutator machines for the power-factor control of said propulsion motors.

9. The combination with railway propulsive apparatus embodying a plurality of similar propulsion motors of the induction type and drive wheels of different diameters connected thereto, of two dynamically asso ciated commutator machines, and means for supplying energy derived from the secondary member of a motor connected to a large drive wheel to one of said auxiliary polyphase commutator machines, driving the second polyphase commutator machine thereby, and supplying energy generated in said second machine to the secondary member of a motor connected to a small drive wheel, and a transformer connected between the armature windings of said polyphase con mutator machines and said source, whereby the armature excitation thereof, and thereby the power factor of said propulsion motors, may be adjusted.

10. The combination With a plurality of induction motors operating at different speeds to drive a common load, of a plurality oi mechanically-coupled commutatortype machines, one of which is connected to a motor to act as a frequency-changer.

1.1. In combination with a suppl circuit and a plurality of induction motors, a plurality o1 connnutator-type machines for in terchanging energy between the secondary windings of the two induction motors, and means "for introducing supply-circuit energy directly into one of the secondary inductionmotor circuits.

12. In combination with a supply circuit and a plurality of induction motors, a plurality of commutator-type regulating machines, mechanical means for transmitting energy from one of the commutator machines to the other, and electrical means for transmitting energ from the second commutator machine to the supply circuit.

18. In combination with a plurality of induction machines, a'pluralit oi commutatortype machines electrically connected to the secondary windings thereof for the pur pose of speed regulation, and means in connection with at least one of the commutaton type machines for furnishing excitation independent of the induction motors.

14. In combination with a plurality of induction machines, a plurality of commutator-type regulating machines respec tively connected thereto and electrical and mechanical means whereby one of the commutator machines acts as a motor driving the other commutator machine When the motor connected to the other commutator machine operates so nearly to synchronisu'i that the other motor is not self-propelling.

15. The combination with a plurality of induction motors operating at different speeds, of aplurality of commutator machines electricallyconnected to the secondary members thereof but operating at a common speed.

In testimony whereof, I have hereunto subscribed my name this 10th day or April, 1920.

RUDOLF E. HELLMUTEID. 

